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AuthorTopic: 32MB for your Amiga for 22$ ?  (Read 1762 times)

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  • Guest
32MB for your Amiga for 22$ ?
« on: March 06, 2007, 06:12:55 AM »
After a bit of investigation, the cheapest source of RAM for my 3000s is ZIPs from Software Hut at 4$ each.

For 16MB that's 128$. That smells outrageously expensive.

One of the reasons why it is not possible to use just any type of RAM in a 3000 is because of the memory refresh system impersonated by RAMSEY.

However, the 3000 and the 4000 have one major advantage, they support Zorro III which allows for 32 bit communication and a very large addressing range. I remember seeing Zorro III expansion cards for the 3000 that could carry up to 64MB of RAM back in the early 90s.

The reason why most RAM expansion boards are expensive is because they require refreshing systems. But today, there are very cheap memory chips that require no refreshing. Their just too slow for most ordinary PCs but slow being a relative thing, they are fast enough for just about any 68k based Amigas with 70ns response time.

Nicer even, they don't use multiplexed address lines.

I found this chip on Digikey which can be purchased by the unit for 11$ each: http://download.micron.com/pdf/datasheets/psram/BurstCellularRAM1.5_128Mb.pdf

This chip has 16 data lines and contains 128Mb of data therefore two of them fullfills the 32bit data bus requirement for 68030, 040 and 060 processors and give you 32MBytes for 22$. It requires absolutely no refreshing but it has a drawback. It operates at low voltage... therefore it would require a couple of 1$ voltage buffers to be usable with Amiga which mostly all operate at 5V. Biiiiiig deal!

Am I just plain stupid to believe that a very cheap board could use these chips to offer large amounts of RAM at a very low cost to Amiga users?

Or is there some serious technical hurdle that prevents these chips from working fine with Amiga computers?
 

Offline ChaosLord

Re: 32MB for your Amiga for 22$ ?
« Reply #1 on: March 06, 2007, 06:26:38 AM »
I have been buying RAM for $45.00 for 512MB anytime I feel like it since November 2004.  These are not bulk purchases.  I just walk into the local computer store and buy 1 whenever I need one.  Why don't you make a board to use it?

I can't believe you are trying to charge people $22.00 for only 32 MB of ram.  That smells outrageously expensive.
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  • Guest
Re: 32MB for your Amiga for 22$ ?
« Reply #2 on: March 06, 2007, 07:21:27 AM »
Quote

ChaosLord wrote:
I have been buying RAM for $45.00 for 512MB anytime I feel like it since November 2004.  These are not bulk purchases.  I just walk into the local computer store and buy 1 whenever I need one.  Why don't you make a board to use it?

I can't believe you are trying to charge people $22.00 for only 32 MB of ram.  That smells outrageously expensive.


Well, I wish you real good luck getting the corner PC store's DDR SDRAM to work on a 68k based Amiga... The reason why such incredibly complex memory systems cost so little (the dram access, refresh and control systems of most modern PCs) is simply because they are sold by the millions.

If there was a board that would allow DDR SDRAM (and SDRAM stands for SYNCHRONEOUS DYNAMIC RAM, not static) to be used on an Amiga it would probably cost no less than 100'000$ to develop. When you can spread this cost across millions of units you know will sell, that's not a problem. The Amiga community doesn't have such a large user base to justify that.

By contrast, static RAM requires no refreshing, no multiplexing of the address lines and consumes incredibly little power. Static RAM is very popular in non-PC digital systems where simplicity of the design is important.

Static RAM chips require incredibly less technical expertise to use because technically speaking, they can be connected directly to the processor's bus without any special chips surrounding them, unlike any other form of dynamic RAM.

It think it is fair to assume it could be possible to develop a working prototype of a ZII/ZIII RAM card that uses these chips for around 1000$.

I'm looking for a way to offer more RAM to all Amiga 1200/2000/3000/4000, not a way to dream about unreacheable things.

Still, if you find that expensive, tell yourself that back in 1992, DRAM was 50$ per MB. Today, ZIPs are 8$ per MB but these static RAM chips are 69 cents per MB. A considerable drop. They would also consume less power than a single one of the traditional ZIP chips.
 

Offline motorollin

Re: 32MB for your Amiga for 22$ ?
« Reply #3 on: March 06, 2007, 07:23:52 AM »
Well said eslapion. This sounds like a great project. Good luck with it!

--
moto
Code: [Select]
10  IT\'S THE FINAL COUNTDOWN
20  FOR C = 1 TO 2
30     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NAAAA
40     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NA-NA-NAAAAA
50  NEXT C
60  NA-NA-NAAAA
70  NA-NA NA-NA-NA-NA-NAAAA NAAA-NAAAAAAAAAAA
80  GOTO 10
 

Offline Zac67

Re: 32MB for your Amiga for 22$ ?
« Reply #4 on: March 06, 2007, 07:26:01 AM »
If you want it cheap: read this.
 

  • Guest
Re: 32MB for your Amiga for 22$ ?
« Reply #5 on: March 06, 2007, 07:40:49 AM »
Quote

Zac67 wrote:
If you want it cheap: read this.


Yeah, the SIP, or should I say the "Patience and meticulous" solution.

That implies you still use the onboard system of your Amiga (3000 in that particular case) to refresh and control access to your memory. Well, in the case of the 3000, this means you will always be limited to 16MB of fast RAM.

How many address lines exactly are there on the Z3 bus? I think that's 32 and therefore your fast RAM limit is more like 4GB (but that would probably be 2GB cuz you always have to have the custom chips and the chip RAM somewhere).

But still, at 22$ per slice of 32MB, this means you could get 64MB for 44$ or 128MB for 88$.

Also, static RAM standards change much less often than PC based dynamic RAMs. There also very popular with other systems such as satellite TV receivers and DVD players/recorders because of the low power requirements and easy design.

Any good electrical engineer wants to help?

 

Offline DamageX

Re: 32MB for your Amiga for 22$ ?
« Reply #6 on: March 06, 2007, 08:29:42 AM »
I'm guessing that there is more demand for a Zorro 3 RAM card than Z2 or A1200. Since Z2 cards are relatively cheap and common, and the A1200 expansion port is often used for an accelerator (and both have limitted address space). Take a look here:
http://www.thule.no/haynie/zorroiii/docs/zorro3.pdf

I bet you could avoid the autoconfig stuff and put the memory at a fixed address (or have a choice of addresses by jumper setting). Then run a utility in startup-sequence to add the memory.
 

Offline motorollin

Re: 32MB for your Amiga for 22$ ?
« Reply #7 on: March 06, 2007, 08:46:24 AM »
If you're planning to build a Zorro RAM expansion, why not build it to accept DDR/SDR? Is that possible?

--
moto
Code: [Select]
10  IT\'S THE FINAL COUNTDOWN
20  FOR C = 1 TO 2
30     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NAAAA
40     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NA-NA-NAAAAA
50  NEXT C
60  NA-NA-NAAAA
70  NA-NA NA-NA-NA-NA-NAAAA NAAA-NAAAAAAAAAAA
80  GOTO 10
 

Offline Oli_hd

Re: 32MB for your Amiga for 22$ ?
« Reply #8 on: March 06, 2007, 10:25:08 AM »
Quote
One of the reasons why it is not possible to use just any type of RAM in a 3000 is because of the memory refresh system impersonated by RAMSEY

Ermm, 30 pin and 72 pin SIMMs would run just fime from the Ramsey timing.. ok you couldnt stick SD-Ram in but a 72 pin adaptor would be much easier to do. (And has been done before, including free designs available from Aminet today)

Quote
I found this chip on Digikey which can be purchased by the unit for 11$ each: http://download.micron.com/pdf/datasheets/psram/BurstCellularRAM1.5_128Mb.pdf    This chip has 16 data lines and contains 128Mb of data therefore two of them fullfills the 32bit data bus requirement for 68030, 040 and 060 processors and give you 32MBytes for 22$. I

Ermm its a 16 bit chip that gives you eight megabyte of memory, sticking two side by side (Connected to the same address pins) would give you 16, an address decoder would be needed for 32. (and four memory chips)

Quote
I can't believe you are trying to charge people $22.00 for only 32 MB of ram. That smells outrageously expensive.      Well, I wish you real good luck getting the corner PC store's DDR SDRAM to work on a 68k based Amiga...

I think he was commenting on your use of "outrageously expensive" when talking about the ZIP ram, it isnt expensive (Your not ment to use it for adding loads of ram, at 1meg its cheap) its just there are cheaper options, you give the BGA memory chip, he gives you PC DDR Ram.

Quote
How many address lines exactly are there on the Z3 bus? I think that's 32 and therefore your fast RAM limit is more like 4GB (but that would probably be 2GB cuz you always have to have the custom chips and the chip RAM somewhere).

Actually 31, it doesnt support 8 bit reads, it reads 16bit at a time minimum, regardless wether or not only 8 bits are in use. but thats a nothing reply, yes the CPU is 32 bit and it can address 4GB total.

Quote
Take a look here:  http://www.thule.no/haynie/zorroiii/docs/zorro3.pdf    I bet you could avoid the autoconfig stuff and put the memory at a fixed address (or have a choice of addresses by jumper setting). Then run a utility in startup-sequence to add the memory.

Actually that card uses ZIP ram too, although adding 72 pin SIMM slots would be a piece of cake. Its a good design and if you wanted to make a memory card that is the design you should use. Upping the maximum RAM is just a matter of adding another 74257 (or 258) to get the extra address lines as the Miggy will detect how much ram is on the card.

Its also a lot easier than your BGA memory chip which would still require logic chips as CRE and ADV would have to be generated.

Quote
If you're planning to build a Zorro RAM expansion, why not build it to accept DDR/SDR? Is that possible?

It is, Xilinx have a design you can download, as do opencores I think.
All someone has to do is try... oh but they will have to add autoconfig and make sure the output bus is 68K compatiable. Also SD and DDR ram are clocked memory, the Zorro bus is asyncronous memory, its not great to mix the two busses... that said you look at 90% of Z3 boards and they are syncronous.
Get designing people. :)

eslapion: To sum up, designing a 72pin SIMM board would be much easier for a hobbiest to do than to start playing around with high density BGA chips.
32Meg 72 pin Simms are still available new, cheap, from most PC suppliers. Eclipse computers here in the UK sell them for £5.82 each. Make a Fastlane type board with 16 72 pin slots and you get half a gig for less than £100
 

Offline HyAmi

Re: 32MB for your Amiga for 22$ ?
« Reply #9 on: March 06, 2007, 11:35:27 AM »
Given Oli_hd's explanation, would it be reasonable to ask Individual Computers to build such boards? Jens and his crew coped with autoconfig and such things before.

If it's easy enough for them, only demand would be an issue.
 

Offline Oli_hd

Re: 32MB for your Amiga for 22$ ?
« Reply #10 on: March 06, 2007, 11:49:11 AM »
yup, get a list of people who would be interested, hand it to Jens and see.
I dont know what Jens is working on now, it may be an ideal time to ask.
 

Offline Jeff

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Re: 32MB for your Amiga for 22$ ?
« Reply #11 on: March 06, 2007, 11:59:11 AM »
Lets start a list of potential buyers somewhere then. Any idea what a DKB 3128 goes for these days if you can find one:-D?

-Jeff
 

Offline Oli_hd

Re: 32MB for your Amiga for 22$ ?
« Reply #12 on: March 06, 2007, 12:02:06 PM »
Quote
Any idea what a DKB 3128 goes for these days if you can find one?

About $150 USD, more for a Fastlane (Specially if the guy words it like it "may" have the 256Meg upgrade)
Aim at £100 and it would be Jens most expensive card I think, so thats a good target.
512Meg Z3 memory card please.
 

Offline Ral-Clan

Re: 32MB for your Amiga for 22$ ?
« Reply #13 on: March 06, 2007, 03:10:52 PM »
My interest is certainly piqued by the thought of being able to use common ram SIMMs in an A3000 card.  I have an A3000 as my backup Amiga.

However, my main Amiga is an A2000, am I correct in stating that the A2000 does not have the same capabilities as the A3000 for Zorro slot RAM expansion?  i.e. it can only accept a max of 8MB on the Zorro slots, or has trouble DMAing to a processor in the accelerator slot?  Even if it were possible it would be slow 16-bit RAM, right?

Basically, wanting a 128MB RAM card on a Zorro II card for the A2000 is just an impossible dream, right?  
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Offline JimS

Re: 32MB for your Amiga for 22$ ?
« Reply #14 on: March 06, 2007, 03:36:46 PM »
Speaking of Xilinx, there are several FPGA dev boards out there that have DDR ram already installed. Up to 32MB ore more. They have free cores to interface the DDR ram as if it were static ram. Why not simply use one of those boards on a carrier designed to fit the Zorro slot?

A board like This one from XESS is only 89 bucks... and it has ps/2 and VGA ports which open up other fun possibilities. ;-)
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